FUSARIUM SPECIES ON BRITISH CEREALS: FUSABIUM NIVALE (FR.) CES. (=?CALONECTBIA GRAMINICOLA (BERK. & BR.) WR.)

Abstract

SUMMARY.1. F. nivale (?Calonectria graminicola) was commonly present along with one or more other species of Fusarium on the basal parts of oats and perennial rye‐grass that had failed in a field. The pathogenicity of the other species of Fusarium being known from previous investigations, that of F. nivale remained to be ascertained.2. In wheat, barley, oats and rye, this fungus causes some loss of plants before or after brairding, and it acts as a continuous check on the growth of established plants sown and grown under adverse conditions, whether infection arises from contaminated soil or seed; good growing conditions largely counteract the effects of contamination.3. F. nivale also attacks ears and grain, preventing grain formation or causing discoloration of formed grains; whilst possible thus to reduce the yield and market value, such attacks are rare in the field.4. The chief result arising from contaminated soil or seed in practice is a general reduction in vigour, a condition more likely to be attributed to causes other than the true one.5. Perennial and Italian rye‐grasses on contaminated soils are reduced first in growth; subsequently, the former is largely killed off by the end of the season, but in the field this stage would be reached in the second season.6. F. nivale grows vigorously within the range of normal summer shade temperature, its optimum being 20–21° C.; it grows slowly at 0–1° C, and in its vegetative state withstands winter conditions, as well as exposure to temperatures as low as – 20° C.; it ceases growth, and loses vitality within a few days, at 32–33° C.7. In culture the fungus grows on media of hydrogen‐ion concentration from 2–5 to 13, the optimum being 6–5 to 6–9; its conidia do not germinate in media more acid than pH 5–0 to 5–2. Neither the existence nor the pathogenicity of the fungus is appreciably affected by the acid or alkaline condition of soils within ordinary field ranges.8. Comparative cultural studies of the British and Continental strains of F. nivale show that they differ consistently and significantly in size of conidia, and in form and rate of growth on certain selective media. These morphological and physiological differences are accompanied by difference in pathogenicity, the Continental strain, so far as has been tested, being more virulent toward cereals and less virulent toward grasses than the British strain.The writer tenders thanks to Dr G‐. H. Pethybridge for helpful criticism of this paper.